The boat handles very well. It tracks a straight course. It's quite a bit more stable than I expected, given its relatively narrow width (23.6"). We took a few motorboat wakes broadside during the race, without any hint of instability. The fore and aft cutouts in the deck allow for smooth, rapid paddling without the risk of bashing the blade into the deck.
Mine is the carbon/kevlar version. It's a sleekly designed and well-manufactured boat. It came with both over- and under-the-stern rudders, with the over-the-stern version installed. I've left it that way for the time being. It has forward and aft watertight compartments, in the style of a typical sea kayak. I flooded the rear compartment the first time out, drowning my cell-pone in the process. I guess you have to plug the under-the-stern rudder port when it's not in use, although Nelo does not seem to have provided any special means for doing so. Duct tape to the rescue, for now!
At about fifty pounds, the Waterman is only half the weight of the plastic tandem sea kayak that its replacing. Huffing it up onto my car's kayak rack is a manageable proposition. It will certainly save me on chiropractor bills! We managed the two short (hundred meter) portages in the Lake Placid race at a slow trot.
I've notices two negatives, so far:
First, while the Waterman has fully-adjustable seats and foot braces, some of the thumb screws are in recessed places that make adjustments difficult. Furthermore, adjusting the front foot brace requires loosening and then retying the rudder cables (at the rudder), which is rather a pain, especially since care needs to be taken to recenter the rudder. This is not a boat that can be quickly reconfigured for friends.
Second, the cockpits are rather short, especially for a tall (6'2") guy like me. I had to carefully design body motions to side myself in. I'm definitely going to have to practice deep-water re-entry before venturing offshore. Once seated, I found the boat to be quite comfortable.
Given it's narrowness and consequent limited cargo space, the Waterman is definitely a day boat and not one designed for long camping trips. That suits me fine. I'm looking forward to paddling it through Maine bays this summer.
The front features the aforementioned tiller bar, and this is where I have to give less than glowing praise. I've spent about three hours in the front of the boat, my partner a little more time, and we both find it very hard keep the boat tracking. My boat has an aftermarket overstern rudder, so the factory underhung rudder may perform better, though it is quite small for a open water K-2.
The boat surfs well in small seas, and the low volume hull pushes through oncoming waves quite nicely. It's a great boat for protected and open water, though there is insufficient storage room to do more than a day tour. The boat does feature decklines all around, so in a pinch you might be able to strap on enough gear to overnight.
Similar boats paddled are the Ruahine Adventure Duet, I might give a nudge to the Nelo, simply because of it's more robust construction. It's a more sporting boat than the Australian Mirage Double, but less practical as it's really a day racer. Still far more fun to paddle than the more utilitarian Seaward Passat. I give it an eight because I haven't figured out how to keep it tracking, and no Kayak gets a 10, otherwise we'd have no need to own multiples of them.